Example 1

Evaluate the expression 3x2 + 5xy – 2 for x = 3 and y = -2.

Hint

plug in 3 for x and -2 for y

Answer

-5

Example 2

The formula for the surface area of a cone is πrs + πr2, where r is the radius of the base and s is the length of the slant. Find the surface area of a cone with radius 10 cm and a slant of 12 cm (use 3.14 for π).